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SubjectOpportunistic S0ix blocked by e1000e when ethernet is in use
Date
Hi Jeffrey,

There are several platforms that uses e1000e can’t enter Opportunistic S0ix
(PC10) when the ethernet has a link partner.

This behavior also exits in out-of-tree e1000e driver 3.4.2.1, but seems
like 3.4.2.3 fixes the issue.

A quick diff between the two versions shows that this code section may be
our solution:

/* Read from EXTCNF_CTRL in e1000_acquire_swflag_ich8lan function
* may occur during global reset and cause system hang.
* Configuration space access creates the needed delay.
* Write to E1000_STRAP RO register E1000_PCI_VENDOR_ID_REGISTER value
* insures configuration space read is done before global reset.
*/
pci_read_config_word(hw->adapter->pdev, E1000_PCI_VENDOR_ID_REGISTER,
&pci_cfg);
ew32(STRAP, pci_cfg);
e_dbg("Issuing a global reset to ich8lan\n");
ew32(CTRL, (ctrl | E1000_CTRL_RST));
/* cannot issue a flush here because it hangs the hardware */
msleep(20);

/* Configuration space access improve HW level time sync mechanism.
* Write to E1000_STRAP RO register E1000_PCI_VENDOR_ID_REGISTER
* value to insure configuration space read is done
* before any access to mac register.
*/
pci_read_config_word(hw->adapter->pdev, E1000_PCI_VENDOR_ID_REGISTER,
&pci_cfg);
ew32(STRAP, pci_cfg);

Is there any plan to support this in the upstream kernel?

Kai-Heng

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